Oceanography is an increasingly important field that contributes information useful to a wide variety of industries. Real-time telemetry from deepwater oceanographic current moorings is especially desirable for the offshore oil industry. Compared with traditional in-situ recording, telemetry of ocean current data allows immediate use of the information, continuous verification of sensor performance, and data security. For example, when an in-situ recording device is lost or irreparably damaged subsequent to collecting a substantial amount of data, the data is also lost. Such losses can be extremely costly, especially if data collection occurs infrequently.
While real-time telemetry from deepwater moorings has been attempted as an alternative to in-situ recordings, real-time telemetry is traditionally very difficult and expensive. Telemetry systems require radio transmission, and radio transmission must occur at the surface of the body of water. Much of the profiling and oceanographic data collection, on the other hand, occurs beneath the ocean surface at depths ranging from a few meters to full ocean depth (thousands of meters). Accordingly, existing systems often utilize an assembly of subsurface buoys and floats that span the desired measurement range from near the surface down to the ocean floor. Such systems also include a data link of some form, which relays information gathered by oceanographic sensors up to the one or more surface components.
However, one problem confronting existing real-time telemetry systems is that surface conditions are extremely harmful to the surface components. As a result, maintaining surface buoys/floats or powered station-keeping surface vehicles often requires excessive attention and resources. Marine biofouling and damage from wave action create a need for continual repairs and tend to involve heavy power consumption. The reliability and operational lifetime of such surface-dwelling telemetry buoys is extremely limited given these factors, and the work required to maintain such systems is burdensome and expensive.
Some attempts have been made to eliminate the need for anchored surface floats or surface stations from such oceanographic measurement assemblies. Recently, autonomous vehicles of various types have been proposed as alternatives to moored surface buoys. Autonomous Surface Vehicles (ASVs), such as long-duration, diesel-powered, boat-shaped vehicles have been offered. Subsurface Autonomous Underwater Vehicles (AUVs) exist that use storage batteries to provide propulsive power. Other subsurface options include winged Autonomous Underwater Vehicles (Gliders), which rely on battery-powered buoyancy changes and lifting surfaces (“wings”) to provide forward propulsion.
However, all existing ASVs and AUVs suffer from very limited propulsive power, which makes them unable to remain in position for an indefinite period, to hold position in storms, or to swim against strong currents, such as the Gulf Loop Current and its eddies (4+ kt) in the Gulf of Mexico, which is just one example of a prime area where real-time current measurements are needed by the offshore oil industry. Furthermore, ASVs must remain at the surface where they are subject to biofouling and possible swamping/damage during storms or especially strong currents. Glider AUVs are extremely limited in power capacity and thus are not equipped to provide frequent real-time telemetry. Rather, they must spend a majority of their time propelling forward underwater, simply to remain on station. This forward propulsion occurs far from the subsurface moored current meters, making trips to the surface for telemetry virtually impossible during such conditions. Additionally, autonomous ocean vehicles are typically very expensive and can have high operational costs due to the required continual attention from skilled technical personnel.
Given the desirability of data collection in such harsh ocean environments, no existing telemetry platform meets the needs of the consumers and the demands of the environment.